Convection based cooking method with flow of combined heated air and steam

ABSTRACT

A convection based cooking apparatus with an insulating baffle to provide improved air-flow and isolation between a cooking chamber and a heating chamber. The heating chamber and the cooking chamber are positioned side by side, and separated by the insulating baffle. The insulating baffle is hollow for holding a liquid and includes an opening for emitting steam. An air passage exists between the heating chamber and the cooking chamber, in such a way that, heated air passes through the passage, flows over the insulating baffle to combine with the steam, and then into the cooking chamber. The air passage is located near the top of the heating chamber and the cooking chamber. As the air passes over the insulating baffle, the air is diffused throughout the cooking chamber and thereby uniformly distributed across a cooking surface within the cooking chamber.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of U.S. application Ser. No. 09/083,416,filed May 22, 1998, now U.S. Pat. No. 6,038,964, which claims thebenefit of U.S. Provisional Application Ser. No. 60/061,042, filed Sep.26, 1997.

TECHNICAL FIELD

The present invention relates to convection ovens, grills, and similarcooking apparatus and, more specifically, to a convection based cookingapparatus with improved air-flow and heat distribution.

BACKGROUND OF THE INVENTION

Convection ovens, convection heaters, hot air balloons, etc. operate onthe principle that the density of air and the temperature of air areinversely proportional to each other. In more familiar words, hot airrises. Within the context of convection ovens, grills or cookers, thisprinciple is used for cooking items without having to expose the itemsdirectly to a flame or heating element.

In state of the art convection ovens, grills, or cookers, a heatingelement is usually positioned to the side and below a cooking surface.As air is heated by the heating element, the heated air is drawn upthrough the cooking surface. Problems that exist in these knownconvection ovens include the inability to uniformly distribute theheated air over the cooking surface and the inability to uniformlydistribute the heat. These problems result in varying cooking rates foritems located at different positions on the cooking surface. The lack ofuniform distribution of the heated air, among other reasons, can beattributed to poorly designed air-flow through the convection oven. Thelack of uniform heat distribution, among other reasons, can beattributed to a failure to insulate the cooking surface from the heatingelement. As a result, items on the cooking surface that are located inclose proximity to the opening to the heating element cook at a higherrate than items located further from the opening.

Therefore, there is a need in the art for a convection oven thatprovides a more uniform distribution of heated air over the cookingsurface. In addition, there is a need in the art for a convection oventhat provides insulation between the cooking surface and the heatingelement.

SUMMARY OF THE INVENTION

The present invention solves the above-identified problems in the art byproviding a method and apparatus for insulating a cooking surface from aheating element and uniformly passing heated air over the cookingsurface. The cooking apparatus of the present invention comprises aheating chamber and a cooking chamber separated by an insulating baffle.

In an exemplary embodiment, the heating chamber and the cooking chamberare positioned side by side, separated by the insulating baffle. Theinsulating baffle is hollow for holding a liquid and includes an openingin the top for emitting steam. An air passage exists between the heatingchamber and the cooking chamber to allow heated air to pass through thepassage, flow over the insulating baffle to combine with the steam, andthen flow into the cooking chamber. In the exemplary embodiment, the airpassage is located near the top of the heating chamber and the cookingchamber. As the air passes over the insulating baffle, the air isdiffused throughout the cooking chamber and thereby uniformlydistributed across a cooking surface within the cooking chamber.

In an alternate embodiment, the insulating baffle is detachable. In yetanother embodiment, the cooking chamber is stacked on top of the heatingchamber.

Accordingly, it is an object of the present invention to provide animproved convection oven. It is another object of this invention toprovide a convection oven that provides insulation between the cookingsurface and the heating element.

It is a further object of the present invention to provide a moreuniform distribution of heated air over the cooking surface.

It is a further object of the present invention to provide an insulatingbaffle and reservoir within a convection oven to insulate the cookingsurface and the heating element, and to interject steam into theair-flow of the convention oven.

Other objects, features and advantages of the present invention willbecome apparent upon review of the following detailed description of theembodiment of the present invention when taken in conjunction with thedrawings and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-section view illustrating the convection flow of anexemplary embodiment of the present invention.

FIGS. 2 and 3 illustrate end views of the embodiment of FIG. 1, with theupper section respectively raised and lowered.

FIG. 4 is a cross-section side-view of the cabinet interior of theembodiment of FIG. 1.

FIG. 5 is a cross-section top-view of the cabinet interior of theembodiment of FIG. 1.

FIG. 6 is a cross-section view of an alternate embodiment of the presentinvention.

FIG. 7 is a cross-section view of another alternate embodiment of thepresent invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention is directed towards providing a convection basedcooking apparatus. One aspect of the present invention includesproviding an insulating baffle between a cooking element and the cookingsurface of the cooking apparatus. Another aspect of the presentinvention is providing a substantially uniform distribution of heatedair across the cooking surface of the cooking apparatus. Another aspectof the present invention is providing a reservoir that can be used toadd seasoning to items cooked within the cooking apparatus. Anotheraspect of the present invention is providing horizontally adjacentheating and cooking chambers separated by a baffle to prevent overcooking of items in the cooking chamber.

FIGS. 1-5 illustrate various views of a preferred embodiment of thepresent invention. FIG. 1 is a cross-section view illustrating theconvection flow of an exemplary cooker. A cabinet 1 has surfaces thatdefine a cabinet interior 2. The cabinet 1 can be constructed from cutaluminum sheets, die cast aluminum, or other similar materials and hasan elongate shape with a horizontal longitudinal dimension. The cabinetinterior 2 of the exemplary cooker is divided into two chambers by aninsulating baffle 80 extending across the longitudinal dimension of thecabinet. The two chambers include a heating chamber 40 and a cookingchamber 60. In one embodiment of the present invention, the insulatingbaffle 80 includes a double-walled liquid reservoir for holding aliquid, such as water, liquid smoke, lemon water, or the like. Inanother embodiment of the present invention, the insulating baffle 80 isremovable from the cabinet interior.

The heating chamber 40 is defined by several surfaces including: a backwall surface 41, a front wall surface 42, a lower surface 43, and a sidewall surface 45; and a side surface 82 of insulating baffle 80. An airintake 50 is defined by an opening in one of the cabinet 1 surfacesdefining the heating chamber 40. Preferably, the air inlet 50 is locatedwithin the lower portion of the heating chamber 40. Furthermore, in anexemplary embodiment, the air intake 50 is located on the lower portionof the side wall surface 45; however, the air intake 50 can also belocated on the lower surface 43, or the lower portion of the back wallsurface 41 or the front wall surface 42. In one embodiment, bestillustrated in FIGS. 2 and 3, an adjustable cover 46 is mounted over theair inlet 50. The adjustable cover 46 can be moved into variouspositions to restrict or allow air-flow through the air inlet 50.

In the lower portion of the heating compartment 40, a steel flame grate48 is positioned over a heating element 49. The steel flame grate 48 ispositioned substantially parallel to the lower surface 43 or to atangential line running through the lower surface 43. In an exemplaryembodiment of the present invention, the heating element 49 is a propaneburner that can be attached to a propane tank or some other source ofpropane fuel. Other embodiments may use various other heating elementsincluding, but not limited to, natural gas burners, electric heatingelements, and charcoal.

As previously described, the heating compartment 40 is separated fromthe cooking compartment 60 by the insulating baffle 80. Heated air isconvected from the heating chamber 40 to the cooking chamber 60 throughan air passage 51. In the exemplary embodiment, the air passage 51 isformed by the upper surface 47 of the cabinet 1 and the top of theinsulating baffle 80. However, in other embodiments, the air passage maybe formed only by the insulating baffle 80, or by a combination of theinsulating baffle 80 and other surfaces of the cabinet 1. Thus, the airpassage 51 may exist through, above, to the side, or below theinsulating baffle 80.

The insulating baffle 80 performs at least two functions. First, theinsulating baffle 80 operates to inhibit thermal conductivity from theheating element 49 to the cooking chamber 60. This aspect of the presentinvention advantageously alleviates the tendency for items in thecooking compartment 60, that are in close proximity to the heatingelement 49, to cooking at a higher rate than other items.

The cooking chamber 60 is defined by several surfaces of cabinet 1,including: a back wall surface 41, a front wall surface 42, a lowersurface 43, and a side wall surface 44; and a side surface 84 ofinsulating baffle 80. A cooking surface 62 substantially extends thelength and the width of the cooking chamber 60, and is substantiallyparallel with the lower surface 43 of the cooking chamber 60 ofcabinet 1. The cooking surface 62 is grated to allow air to pass throughthe surface. An air outlet 52 is defined in one of the cabinet 1surfaces defining the cooking chamber 60. Preferably, the air outlet 52is located in the lower portion of the cooking chamber 60. Furthermore,in an exemplary embodiment, the air outlet 52 is located within thelower portion of the side wall surface 44; however, the air outlet 52can also be located on the lower portion of the back wall surface 41,the front wall surface 42 or the lower surface 43. In the preferredembodiment, the cooking surface 62 is positioned so that the uppersurface of the cooking surface is below the air passage 51 and the lowersurface of the cooking surface 62 is above the air outlet 52.

In an exemplary embodiment, a draft chimney 70 is used as a draftgenerator to pull air through the cabinet interior 2 of the cabinet 1.In one embodiment, the draft chimney 70 includes an elongated flue 71with a first opening 72 on one end and a second opening 74 on theopposing end. The draft chimney 70 is fixedly attached to the side wall44 of the cabinet 1 so that the first opening 72 corresponds with theair outlet 52. The elongated flue 71 of the draft chimney 70 verticallyextends upward, substantially parallel to the side wall 44. In thepreferred embodiment, the length of the elongated flue 71 is about fourfeet and approximately two feet of the elongated flue 71 extends abovethe cabinet 1. In an exemplary embodiment, a chimney cap 76 may beattached over the second opening 74 in such a way as to allow air toescape from the second opening 74 but to prevent rain water fromentering the second opening 74.

FIG. 6 is a cross-section view of an alternate embodiment of the presentinvention. In this alternate embodiment, rather than a draft chimney, amotorized fan 77 can be used to create a draft through the cabinetinterior 2. In this embodiment, a fan is positioned over the air outlet52. When the fan is operating, the fan draws air from the cookingchamber 60, thereby creating a draft through the cabinet interior 2. Byadjusting the speed of the fan, the rate of air-flow through the cabinetinterior 2 can be adjusted.

FIG. 7 is a cross-section view of another alternate embodiment of thepresent invention. In this embodiment, a valve 78 is included in thebottom surface of the cooking chamber 60. In this embodiment, a liquidcan be poured into the bottom portion of the cooking chamber 60. Duringcooking, grease and food particles will fall into the liquid. Duringclean up, the valve 78 can be opened and the liquid, grease, and foodparticle mixture can be drained from the cooking chamber 60. Thisembodiment of the present invention allows for easy clean-up of thecooking chamber 60.

As best seen in FIGS. 2 and 3, the cabinet 1 can be configured toinclude an upper section 3 and a lower section 4. The upper section 3and the lower section 4 are attached along a common edge of the backwall surface 41 by a hinging member 12. This configuration allows theupper section 3 to be rotated, along the hinged axis, between an openposition as shown in FIG. 2, and a closed position as shown in FIG. 3.In an alternative embodiment, the upper section 3 and the lower section4 are permanently attached and an access door or panel is provided inthe upper section 3.

In an alternative embodiment, the heating chamber 40 and the cookingchamber 60 are vertically aligned with the heating chamber 40 positionedunder the cooking chamber 60. In yet another alternative embodiment, theheating chamber 40 can be positioned over the cooking chamber 60. Ineach of these embodiments, the insulating baffle 80 is positionedbetween the heating chamber 40 and the cooking chamber 60 and an airpassage 51 allows heated air to pass from the heating chamber 40 intothe cooking chamber 60.

OPERATION OF THE DISCLOSED EMBODIMENT

In operation, ambient air enters the heating chamber 40 through the airinlet 50. The ambient air is heated by heating element 49. As the air isheated, the air rises through the steel flame grate 48 towards the topof the heating chamber 40. Eventually, the heated air is forced throughthe air passage 51 and into the cooking chamber 60. As the heated air isforced into the cooking chamber 60, the cooler air previously existingin the cooking chamber 60 is forced down and out the air outlet 52.Eventually, as additional heated air is forced into the cooking chamber60, some of the heated air is also forced through the air outlet 52,first opening 72, and into the elongated flue 71 of the draft chimney70. The heated air that is forced into the elongated flue 71 of thedraft chimney 70 rises to the top of the elongated flue 71 and exits theelongated flue through the second opening 74. As the heated air risesthrough the elongated flue 71 of the draft chimney 70, a vacuum, similarto a siphon, is generated to draw additional air through the interior 2of the cabinet 1. The rate of the air-flow through the interior 2 of thecabinet 1 can be controlled by adjusting the adjustable vent 46 over theair intake 50. In addition, the rate of air-flow can be controlled byadjusting the temperature of the heating element 49.

It should be appreciated that the draft chimney 70 operates to produce astrong draft through the cabinet interior 2. Thus, when the adjustablevent 46 is fully open, a high rate of air-flow can be realized throughthe cabinet interior 2. This condition allows items on the cookingsurface 62 to be cooked quickly. Alternatively, the adjustable vent 46can be adjusted to a substantially closed position. This conditionallows the rate of air-flow to be decreased, thereby allowing items onthe cooking surface 62 to be cooked at a slow rate. In the embodimentusing a fan to create a draft, the same principle applies. However,varying the speed of the fan can also be used to increase or decreasethe rate of air-flow through the cabinet interior 2.

The insulating baffle 80 operates to disperse the air-flow of the heatedair throughout the cooking compartment 60. Additional baffles may alsobe added to further alter the air-flow. This aspect of the inventionallows for an even distribution of the heated air throughout the cookingcompartment 60. As a result, the items on the cooking surface 62 can becooked evenly throughout.

In one embodiment, the insulating baffle 80 is a liquid reservoir. Inthis embodiment, the insulating baffle 80 serves at least two functions.First, the insulating baffle 80 improves the insulation between theheating chamber 40 and the cooking chamber 60. The improved insulationis attributed to the presence of liquid within the reservoir. Theimproved insulation provided by the insulating baffle 80, prevents itemslocated on the cooking surface 62 in close proximity to the heatingelement 49 from being burned or over cooked due to thermal conductivityof the heat. Second, the insulating baffle 80 can be used to help seasonor add moisture to items being cooked on the cooking surface 62. Forexample, liquid smoke can be added into the reservoir of the insulatingbaffle 80, allowing the smoke to permeate the items being cooked on thecooking surface 62. As another example, lemon juice and water can beplaced into the reservoir of the insulating baffle 80 to provide lemonseasoning to the cooked items. In addition, the steel flame grate 48 canbe used to support other flavor enhancing materials. For example,various types of woods, nuts, spices, or the like, can be placed on thesteel flame grate 48 over the heating element 49. As these items areheated, the smoke generated from these items provides seasoning to theitems being cooked.

As previously mentioned, one embodiment utilizes an insulating baffle 80that can be detached and removed from the interior 2 of the cabinet 1.This embodiment advantageously allows the insulating baffle 80 to beremoved and cleaned between uses.

Although the present invention has been described in various embodimentshaving various measurements and shapes, it should be understood that thepresent invention is not limited to any particular shape, size, orconfiguration. On the contrary, the aspects of the present invention canbe embodied in various manners within the scope and spirit of theinvention as described herein.

I claim:
 1. A method for providing an air-flow of combined heated air and steam in a convection cooking apparatus, the method comprising the steps of:receiving air through an inlet into a heating chamber; heating the air within the heating chamber; heating liquid contents of a hollow baffle located adjacent to the heating chamber; releasing steam from the hollow baffle into a passage between the heating chamber and a cooking chamber; drafting the heated air from the heating chamber through the passage into a cooking chamber, thereby combining the heated air with the steam; passing the combined heated air and steam into the cooking chamber over and though a cooking surface; and venting the combined heated air and steam out of the cooking chamber through an outlet.
 2. The method of claim 1, wherein the heating chamber and the cooking chamber are positioned side by side, and said step of drafting the heated air from the heating chamber through the passage into a cooking chamber comprises, drawing the heated air into a first opening of the passage located near the upper portion of the heating chamber, mixing the heated air with the steam within the passage, and venting the combined heated air and steam into the cooking chamber through a second opening of the passage located near the upper portion of the cooking chamber. 